One type of image forming apparatus well known in the art that employs an electrophotographic technology is a tandem-type image forming apparatus. This type of image forming apparatus includes a developing roller, a photosensitive member, and a transfer roller for each of the colors yellow, magenta, cyan, and black, for example. During image formation, each developing roller supplies developer in each respective color onto each respective photosensitive member to form a developer image in the respective color. Each developer image is transferred sequentially onto a sheet of paper conveyed along the photosensitive members.